[Show abstract][Hide abstract] ABSTRACT: Non-healing foot ulcers are the most common cause of non-traumatic amputation and hospitalization amongst diabetics in the developed world. Impaired wound neovascularization perpetuates a cycle of dysfunctional tissue repair and regeneration. Evidence implicates defective mobilization of marrow-derived progenitor cells (PCs) as a fundamental cause of impaired diabetic neovascularization. Currently, there are no FDA-approved therapies to address this defect. Here we report an endogenous PC strategy to improve diabetic wound neovascularization and closure through a combination therapy of AMD3100, which mobilizes marrow-derived PCs by competitively binding to the cell surface CXCR4 receptor, and PDGF-BB, which is a protein known to enhance cell growth, progenitor cell migration and angiogenesis.
Wounded mice were assigned to 1 of 5 experimental arms (n = 8/arm): saline treated wild-type, saline treated diabetic, AMD3100 treated diabetic, PDGF-BB treated diabetic, and AMD3100/PDGF-BB treated diabetic. Circulating PC number and wound vascularity were analyzed for each group (n = 8/group). Cellular function was assessed in the presence of AMD3100. Using a validated preclinical model of type II diabetic wound healing, we show that AMD3100 therapy (10 mg/kg; i.p. daily) alone can rescue diabetes-specific defects in PC mobilization, but cannot restore normal wound neovascularization. Through further investigation, we demonstrate an acquired trafficking-defect within AMD3100-treated diabetic PCs that can be rescued by PDGF-BB (2 μg; topical) supplementation within the wound environment. Finally, we determine that combination therapy restores diabetic wound neovascularization and accelerates time to wound closure by 40%.
Combination AMD3100 and PDGF-BB therapy synergistically improves BM PC mobilization and trafficking, resulting in significantly improved diabetic wound closure and neovascularization. The success of this endogenous, cell-based strategy to improve diabetic wound healing using FDA-approved therapies is inherently translatable.
PLoS ONE 01/2014; 9(3):e92667. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although different cranioplasty storage methods are currently in use, no study has prospectively compared these methods. The authors compare freezing and subcutaneous storage methods in a rat model.
Trephine defects (10 mm) were created in 45 Sprague-Dawley rats. The cranial bone grafts were stored in an autologous subcutaneous pocket (n = 15), frozen at -80°C (n = 15), immediately analyzed (n = 12), or immediately replanted into the defect (n = 3). After 10 days of storage, the subcutaneous or frozen grafts were either replanted (subcutaneous, n = 3; frozen, n = 3) or analyzed (subcutaneous, n = 12; frozen, n = 12). Grafts underwent histologic analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, alkaline phosphatase assay, mechanical testing, and micro-computed tomographic imaging.
After 10 days of storage, physiologic assays demonstrated a significant decrease in cellular functionality (e.g., alkaline phosphatase assay concentration: fresh, 18.8 ± 0.77 mM/mg; subcutaneous, 12.2 ± 0.63 mM/mg; frozen, 8.07 ± 1.1 mM/mg; p < 0.012 for all comparisons). Mechanical integrity (maximal load) of fresh grafts was greatest (fresh, 9.26 ± 0.29 N; subcutaneous, 6.27 ± 0.64 N; frozen, 4.65 ± 0.29 N; fresh compared with frozen, p < 0.001; fresh compared with subcutaneous, p = 0.006). Replantation of subcutaneously stored and frozen grafts resulted in limited bony union and considerable resorption after 12 weeks; in contrast, replanted fresh grafts demonstrated bony union and little resorption.
Current preservation methods for interval cranioplasty do not maintain bone graft viability. Subcutaneous storage appears to provide a small advantage compared with freezing.
Plastic and reconstructive surgery 05/2011; 127(5):1855-64. · 2.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Primary alveolar cleft repair has a 41 to 73 percent success rate. Patients with persistent alveolar defects require secondary bone grafting. The authors investigated scaffold-based therapies designed to augment the success of alveolar repair.
Critical-size, 7 x 4 x 3-mm alveolar defects were created surgically in 60 Sprague-Dawley rats. Four scaffold treatment arms were tested: absorbable collagen sponge, absorbable collagen sponge plus recombinant human bone morphogenetic protein-2 (rhBMP-2), hydroxyapatite-tricalcium phosphate, hydroxyapatite-tricalcium phosphate plus rhBMP-2, and no scaffold. New bone formation was assessed radiomorphometrically and histomorphometrically at 4, 8, and 12 weeks.
Radiomorphometrically, untreated animals formed 43 +/- 6 percent, 53 +/- 8 percent, and 48 +/- 3 percent new bone at 4, 8, and 12 weeks, respectively. Animals treated with absorbable collagen sponge formed 50 +/- 6 percent, 79 +/- 9 percent, and 69 +/- 7 percent new bone, respectively. Absorbable collagen sponge plus rhBMP-2-treated animals formed 49 +/- 2 percent, 71 +/- 6 percent, and 66 +/- 7 percent new bone, respectively. Hydroxyapatite-tricalcium phosphate treatment stimulated 69 +/- 12 percent, 86 +/- 3 percent (p < 0.05), and 87 +/- 14 percent new bone, respectively. Histomorphometry demonstrated an increase in bone formation in animals treated with hydroxyapatite-tricalcium phosphate plus rhBMP-2 (p < 0.05; 4 weeks) compared with empty scaffold.
Radiomorphometrically, absorbable collagen sponge and hydroxyapatite-tricalcium phosphate scaffolds induced more bone formation than untreated controls. The rhBMP-2 added a small but significant histomorphometric osteogenic advantage to the hydroxyapatite-tricalcium phosphate scaffold.
Plastic and reconstructive surgery 12/2009; 124(6):1829-39. · 2.74 Impact Factor